1. Field of the Invention
The present invention relates to an abrasive machine for stones, and more particularly to such machine for grinding-polishing a flat stone surface with the flat surface of a circular rotary abrasive disk tool of which the vertical position is made adjustable in relation to the stone surface.
Various kinds of stones such as marble, granite and the like have been used for various purposes. Depending on the purposes or uses, a fairly large area of stone plate is subjected to grinding and polishing at the exterior side thereof, e.g. for flooring, wall construction and the like.
2. Description of the Prior Art
Hitherto, the abrasion or grinding-polishing of such stone work-piece has been carried out by grinding the stone surface with the flat surface of a circular rotating disk grindstone made of an abrasive material such as particles or chips of natural or synthetic diamond, carborundum or the like and a suitable binder. Such grindstone is detachably mounted on a disk head adapted to be rotated and manually moved over the stone surface. As the polishing progresses, such grindstone is exchanged with a finer grindstone one after another, and finally with a felt for polishing or finishing the stone surface with aid of finely pulverized abrasive material.
In order to avoid troublesome exchange of the grindstone and make the abrasion working efficient, it is possible to arrange a plurality of such grinding machines in series so as to process the work-piece from rough grinding, according to the first machine, to final polishing, according to the last machine. It is inevitable, however, that undulations or uneveness are present on the processed work-piece surface when the stone plate is of fairly large area relative to the dimension of the abrasive tool. This is a result of a suitable width of the stone plate being subjected to grinding by manually driving the rotating abrasive tool to-and-fro over the stone plate surface, and when such area has been treated the work-piece is moved so as to further process a new area of the stone plate. Considerable skill is required for driving such abrasive tool without causing such unevenness. In order to avoid such undersired undulation and make the abrasion working more efficient, it has been considered to enlarge the diameter of the disk grindstone as large as possible. It will be readily understood, however, that there is naturally a limitation in doing so because of the mechanical strength of the formed grindstone on the one hand and of rattling of the rotary disk on the other hand.